SENSITIVE DETERMINATION OF GABAPENTIN IN HUMAN URINE BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH UV–VIS AND FLUORESCENT DETECTION

Two rapid, sensitive, and reproducible methods for the determination of gabapentin (GBP) in urine based on high-performance liquid chromatography (HPLC) with UV-Vis and fluorescent detection, respectively, were developed for the first time using a new synthesized fluorescent label, 6-oxy-(N-succinimidylacetate)-9-(2′-methoxycarbonyl) fluorescein (SAMF). The highest derivatization efficiency was obtained in borate buffer (pH 7.25) at room temperature for 10 min. The chromatographic separation was carried out using a mixture of methanol and water containing 5 mmol l−1 sodium citrate buffer (pH 5) as a mobile phase with UV-Vis detection at λ = 455 nm and fluorescent detection (FLD) at λex/λem = 488/520 nm, respectively. A calibration curve ranging from 1 × 10−8 mol l−1 to 1 × 10−6 mol l−1was shown to be linear. The concentration limit of detection (LOD) was 1 × 10−8 mol l−1 and 2.5 × 10−10 mol l−1(signal to noise ratio = 3) for HPLC-UV-Vis and HPLC-FLD, respectively. The proposed methods were applied to the determination of GBP in urine samples with satisfying results.